His first name appears to be unknown by any of the characters, even his employer; in "The Package" his business card gives his name merely as "NEWMAN".
A minor character calls him "Norman" in "The Bottle Deposit", but this was a mistake on the part of the actress/character, rather than any revelation of Newman's first name.
Newman is petty, vindictive, prone to hysteria, and often depicted as a stereotypical evil genius, who is usually undermined in some way.
Newman and Kramer are usually depicted as casual friends, and the two sometimes participate in various unsuccessful moneymaking schemes together.
A number of actresses made guest appearances as Seinfeld's love interests in single episodes: